Mold and method of making the same



Aug. 1G, 3943 .1. F. KELLY ET A1.

l MOLD AND METHOD OF MAKING THE SAME Filed Sept. 18, 1939 ATTORNEY.

Patented Aug. 10, 1943 MoLD METHOD oF MAKING THE sAME John F. Kelly and william J. Kelly,-

Elkins, W. Va..

Application September 18-,19'3`9, Serial No. 295,551

4 Claims.

This invention relates to bimetallic constructions wherein two metals are united together and i to the process ofv making such constructions.

More specifically, the invention relates to glass molds and to themethod of making as well as using such molds.

The primary object of this invention is to produce a low cost bimetallic construction having one surface thereof suited for glass molding work and in which the ,two parts of the construction are so fused together as to enable eflicient transmission of heat from the cavity to the outer surfaces of the mold. Other objects of the invention will appear as this description proceeds.

In carrying out the above object, we use an inner layer of a chilled corrosion resistant cast iron which defines the cavity of the mold. The material used is preferably a nickel-iron alloy having a nickel content well above 20% although this particular alloy is not essential and our 111- vention may be carried out vwith various heat resistant materials. During the manufacture of this mold, the nickel cast iron part is machined on its outer surfaces so it will be quite clean. It is essential to remove all foreign matter from this surface by a good cleaning process and We have found machining to be quite satisfactory. This vpart is then heated to 1600 F. in a non-oxidizingl medium, transferred to a foundry mold in such a manner that its contact with the air is very brief, and then coated with a very thick layer of cast iron by the step of casting ordinary cast iron about the same. With our process, the ordinary cast iron fuses with the nickel-iron alloy part and thereby creates a very eiiicient heat iiow path from the alloy part to the outer surfaces of the part composed of ordinary cast iron.

The present invention satisfies all the requirements of a good glass mold in that it provides a non-oxidizable molding surface as well as eiilcient heat dissipation from the molding cavity to the outer surfaces of the mold. Moreover, the new mold is inexpensive to manufacture.- can be manufactured without appreciable probability of unreliable operation, and may be used several times for several different shapes of articles. As an example of this latter feature, we point out` that l after using the mold for producing articles of.

must be free from oxidization, and both cast iron as well as pure nickel havel been proposed as materials for such molds.' With such limitationsv has recognized that the surface of a glass mold' as cost, a nickel glass mold cannot be made thick enough so that its outer surface has enough area to eifectively dissipate theheat. It has been proposed to cast a. ring of iron around such a nickel insert, however, in absence of fusionbetween the cast iron and the nickel insert there would be considerable resistance to heatiiow at the junction of the nickel and iron. The present invention contemplates a glass `mold in whichvthe inner stainless part is fused to the outer layer of cast iron, which outer layer is madel very thick so it will have both a large external surface area and a large heat dissipating area. Such a glass mold characterizes the present invention, and we have found it to be a very marked improvement over glass molds known to the prior art.

A proposal that has been made by inventors of the prior art is to weld, by ordinary welding methods; a non-oxidizable coating upon an oxidizable metal but that proposal differs considerably from our invention and it also has certain disadvantages which do not occur with our process. Such prior art molds as we just mentioned are subject to the great disadvantage of being incompletely welded, the disadvantage of having air pockets at the joints, and they can 'ordinarily be built only when simple cavities are used; Accordingly, it is apparent that when the mold of our invention is compared' with molds of the prior art such as the prior molds recited above, it isA metal surface of the chill mold conducts heat away from the `hot iron causing' the latter to cool rapidly. This makes the resultant casting uniform and dense. However, in casting a glass mold such as used by inventors of the prior art,- it is impossible with usual casting methods to get the center or working section of the casting as dense as desired.

With this invention, anl insert is castragainst a chill and since this insert'is relativelythinit becomes very dense throughout. With our process,v an outer'layer may be cast onto aswell as fused to this insert without destroying the high degree of density of the insert. Hence, we can `produce a, glass mold which is very dense in its central working section. To avoid cracking the thin inner part or insert, it. is desirable to use metals for both the inner and `outer layers this disclosure, however. the insert is then covered with a coating of lampwhich have similar coeflicients of thermal expansion as well as similar melting points.

In the drawing:

Figure 1 illustrates apparatus for manufacturing glass articles and includes a container of glass, a glass mold, a plunger, and a valve.

Figure 2 is a top View of the mold of Figure 1 sleeve I surrounds and is fused to the inner nickel-iron alloy part II. While this specification specifies that cast iron is used for layer I0, we recognize that any good heat conductor such as copper or aluminium may be used in forming layer I0 without departing from the very broadest aspects of our invention. The insertl or inner pa'rt I I defines a cavity ISa of a shape, for example, conforming to the outer surface of an ordinary drinking glass. The surface I9 of insert I I is machined to such a shape.

A plunger is often used in glass manufacturing machinery and a suitable plunger is shown in Figure 1 directly above the mold cavity I9a. I'his plunger has a cast iron section I4 with an outer layer I5 of nickel-iron alloy cast iron fused thereto. The surface of layer I 5 conforms to the shape-of the inner side 0f the glass articles to be produced, for example, it may conform to the inner surface of said drinking glass. In addition to the mold and plunger, most glass manufacturing equipment of the type being considered employs a valve which in Figure l is shown directly below the mold cavity |911'. This valve has a white or grey cast iron base I2 with a nickeliron alloy coating I3 fused thereto.

The method of manufacturing glass molds such as those shown in Figure l will now be described, reference being made particularly to Figure 3 although like parts on all figures are represented by like numbers..

in which'a large number of jets 2| emerge tangentially from the inner surface of the furnace 34. The jets 2| are so arranged that a smooth band of fiames exist for a distance` of about three inches from the inner wall of furnace 34. The overall diameter of the furnace is three to five feet, The jets all face in the same angular direction and propel the flames around the inner wall of the furnace. The hot gases pass out the openings 34a respectively located at the top and bottom of the furnace 34.' As a result, the flames and hot gases act on all sides of chamber 22 forcing heat evenly into this small chamber to such an extent that insert II is evenly heated to a temperature well above red heat and preferably to a temperature above 1600* F.

When sufficient times has elapsed for heat to fully penetrate the insert I I to raise the same to say 1600 F. or slightly hotter, the entire small chamber 22 is removed to position 22a where it is adjacent the foundry meld 35. If the insert II were transferred to position l la without using the chamber 22, the insert would oxidize slightly and impair the resultant glass mold. When at position 22a, the lid 23-is removed and the insert I Ia removed and quickly brushed so as to remove the carbon which was deposited or smoked on the insert previously. In event the modified An alloy insert II, of suitable stainless metal such as the alloys described elsewhere in this disclosure, is first cast in a cylindrical chill mold 20 having thick chill walls. The cavity |9a may be cast into the insert originally or it may be machined into the insert immediately after the casting step is completed. Preferably, however, the cavity I9a is machinedA into the mold as the last step in the production of the mold.

After being cast, the outer surface wall-of insert is thoroughly cleaned, preferably by machining the outer part oi' this insert. Any cleaning method that thoroughly cleans the outer surface of part II will be Within the teachings of After being cleaned,

black, or it may be smoked by the smoke from an acetylene torch. This coating is placed on the outer surface of the part Il to prevent the part from being oxidized by 'subsequert steps of the process. Instead/of coating the part II with lampblack, it may be coated with copper by electroplating. The insert II is then placed in chamber 22 which chamber is only slightly larger than the insert II.-This chamber may have a charcoal lining but this is not necessary. A removable cementlidiZil is placed on chamber 22. The chamber 22 is then placed in a gas furnace 34 of any suitable type but preferably a furnace l process is used wherein the insert is coated with copper it is not necessary to remove the coat-v ing. After being brushed, the insert Il is placed in the foundry mold 35 at position IIb. The foundry mold 35 is then quickly assembled and ordinary grey cast iron poured into the cavities a of this foundry mold. A ladle 3| is used to supply the grey cast iron into the sand top 30 which defines the gate 30a. A vent 33 of dry sand core material is` used to remove the hot gases-from the molding chamber within 35. It is understood that the insert II is substantially at 1600 F. at the time the outer layer I0 is cast thereon ,by the process just outlined.

Since the nickel-iron alloy part II is the only part of our mold that comes into contact with the hot glass, it is not absolutely essential that foundry mold `have chill walls although it is desirable that it does. Ordinary sand walls will be satisfactory. The nickel-alloy part I I has excellent' heat and corrosion-resistance yet a melt--v ing-point approximately the same as ordinary cast iron. A11 of the iron alloy compositions described in detail in this disclosure have melting points between 1990 F. and 2280 F. and when such alloys are used in making insert II, it is necessary to heat the insert to only about 1600 F. in furnace 34. The insert II is further heated on its outer surface by the hot cast iron coming into the foundry mold 35 and the temperature of the insert is thereby raised to the fusion point. Hence, the cast iron from ladle 3| thoroughly fuses with insert l| and a wide band of alloy between the two is forme'd in the mld. This widef bandis illustrated in Figure 1 and specifically designated by reference number 36 with respect to the mold, and 31 with4 respect to the plunger. With ordinary welding methods, alloying between the partsvof the resultant mold'would be 're-v stricted to a very narrow band and as a result the junction would be quite inferior to the juncltion of `our invention wherein very intimate associatin of the parts I0 and I I is effected. If an insert II is used which has a melting point higher than 2280 F., it is desirable to heat the insert II to a5 temperature well above 1600 F. before pouring iron from ladle 3|. On the other hand, y

' of new molds.

and the cavity which was produced by the core k IIb machined so as to clean the inner surface thereof. 'I'he outer part I0 is then placed in the furnace 34 and heated almost to its fusion temperature at which time it is used as a mold and the nickel-alloy inner part 'I I poured directly into the cavity of the part I 0. This may be done while part I0 isstill in the -furnace 22 or it may be done after the part I0 is removed from furnace 22, but in any event it must be done While outer part I0 is hot. 'Ihe cavity I9 isk then machined 20 into the inner part-l I I.

As shown in Figure 1, both the plunger and the valve may be of bimetallic construction. Either may be produced by the processes recited above. For example, the nickel-iron alloy piece- I5 may 25 be machined to shape from the cast state1 heated to 1600 F., transferred to a moldy in a suitable smallchamber similar to chamber 22, and cast iron I4 poured thereinto. It is also apparent that part I4 may be cast first and part I5\later. -30 While the nickel-iron alloys contemplated by this invention are relatively stainless it has been found -that after a time, in fact a rather long time as compared to ordinary glass molds, their surfaces become less Veiicient than the surfaces When this occurs, the mold surface may be machined to new dimensions I'I, and the plunger I5 may be machined to new dimensions I8. Further pouring of glass from I6 will produce glasses having a thick wall instead of a 40 thin Wall as originally.

As heretofore stated, the broadest aspects of this invention are not limited to any particular material for either the insent I I or the outer part I0. Suitable materials 'are listed below. The 45 preferred composition for the insert II is:

Perferrcd Mmi- Maxl- Element percentage mum mum 50 Per cent Per cent 3.00 2. 25 3.25 2. 00 1.00 3.00 Manganese. 0.70 0.50 1.00 Chromium 3. 0. 00 6. 00 Nickel 29.00 20.00 50. 00 55 Molybdenum l. 00 0. 00 2. 00 Usual impurities, balance iron.

The above alloy is suitable for use on the surface of the plunger as Well as for use in insert I I. Another alloy suitable for either the insert II G0 or the plunger surface I5 is:

1 Under 1%. 75

Another type of iron whichxmay be used for either the insert Il 0r the plunger surface I5 is:

Preferred Mun- Maxi- 4 Element percent mum mum age Per cent Per cent Totalcarbon 3. 70 3. 00 4. 00 Silicon 2. 10 l. 00 3. 00 Tckel 1. 00 0. 00 2. 00 Chromium 0.10 0. 00 l. 00 Molybdenum 0. 0. 00 1. 00 Balance iron with usual impur- 1 ies.

The above types of alloys as well as the `ones listed below are all melted in a cupola according to standard foundry practice for these general types of irons and poured into permanent molds having thick metal chill walls.

The `cast iron that is poured into the gating 30a of Figure 3, to form the outer layer I0 of Figure l, and the iron used in making the section I4 illustrated also in Figure 1, has a preferred'composition of total carbon 3.5%; and silicon 2.20%. The carbon content works well between the limits of 3.00 to 4.00% and the silicon may vary Within the limits of 1.50% and 2.75%. The balance is iron With usual impurities. This latter yiron may be used for the insert II and surface I5 but it is not as good as the other alloys for that use. It is quite satisfactory for .the insert I I and in fact a mold constructed according to 'our process, even with this type of iron for the insert, is. superior to prior art molds inasmuch as our process enables us to thoroughly chill such a cast iron and thereby greatly improve its qualities above'the qualities that would be obtained if such ordinary cast iron Were used in any ordinary glass mold of the prior art.

Those skilled in the art understandthat any of the cast irons disclosed above, as poured from the cupola, have large quantities of combinedcarbon but upon striking the chill mold precipi- 'tate most of this combined carbon into graphite.

The graphite makes the iron uniform and dense. It is apparent that with our mold, the combined carbon is very eiciently changed Ito graphite adjacent our mold-ing surface I 9.

If our process produces the part I I too hard for it to beA machined, it/ may be suitably annealed toV any desired degree.

We claim to have invented:

1. A device for producing glass articles comprising a part adapted to come into contact with molten glass on one surface thereof, said part being composed principally of ir'on having an alloying element therein in appreciable percentage adjacent said surface and in substantially less percentage at points in said part remote from said surface, that Will render the metal Asubstantially stainless.

2. A glass mold comprising a thin thoroughlyv chilled cast iron cylinder composed of:

r Per cent Carbon 2.25 to 3.25 Silicon 1.00 to 3.00 Manganese 0.50 to 1.00

Nickel 20.00 to 50.00 Balance principally. iron;

and a thick outer sleevesurrounding the outer Asurface of said cylinder, intimately fused thereto,

adapted to-be used with glass molding machinery for molding glassware, said implement being composed of a body of cast iron haying fused thereto a glass engaging portion composed of:

Per cent Carbon 2.25 to 3.25 Silicon 1.00 to 3.00 'Manganese 0.50 to 1.00 Nickel 20.00 to 50.00

Balance principally iron with impurities.

JOHN F. KELLY. WILLIAM J. `KELLY. 

